Engine Technical Question - please reply soon

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Engine Technical Question - please reply soon

Does turning of engine oil black after few hundred KM say 1000 KM is a bad sign? What are all possible causes?

Does Carburetoer settings has any contribution to this.

Secondly please tellif its because of some carburetor adjustment that when switching off the car the engine sometime (not always) jerks 3-4 times or say that it does a dieing 3-4 knocks before switching off. the engine foundation is ok

please reply soon.

Gari.pk User 764 asked on 17 Jun 2010 12:55:11 pm

1 Answer

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Arham - on 17 Jun 2010 12:55:24 pm

Oil color although not significant is nonetheless a very nominal indicator of contamination. Depends on the oil quality and the fuel you're using as well but thats another discussion best saved for another time.
Off the top of my head,if your engine oil is turnig black after a 1000km, it could be that you've excessive blow by caused by weak compression rings causing exhaust gases to leak past the piston. Soot combined with other wear and tear causes the usual change in color. Check to see your oil consumption and to be on the safe side, perform a compression test as well. There's two types of Tests, Dry and Wet, have both done.
As for the other phenomenon, its known as "dieseling" and this is rotation of the engine n the opposite direction and is caused by and as very appropriatly added by Robin, inappropriate valve or spark timing OR running an overly rich mixture.